Aerospace behemoth Boeing has announced that it will build a hybrid airship/helicopter combination aircraft, able to lift heavy loads across long distances. Boeing will work with Canadian firm SkyHook International.
"SkyHook secured the patent for this neutrally buoyant aircraft and approached Boeing with the opportunity to …

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Suddenly buoyant

The obvious thing to do would be to stick a compressor on the gas bags and suck a bit back in to reduce buoyancy, using the rotors and winch system to balance the lift while the load was being released.

You'll still get an enormous lift if you suddenly drop something, I believe this is an issue for the larger gunned helicopters (and the A-10?) which can dump heavy ammunition at an extraordinary rate. Actually fire-fighting aircraft as well...

There was an idea like this a while back with a spinning lifting ball to use aerodynamic lift. Died a death because airships need good weather.

Venting of Helium

It strikes me that it is much more fuel efficient to have extra boyancy than to accelerate a great mass of air downwards to compensate for the dead weight of a load. Surely it's possible to pump helium in and out of the gas bags before letting go of the load. If that takes too long, then taking on compensating ballast in the form of water must surely be possible in many locations.

As for a patent, then surely airship industries used rotating thrusters. OK it had nowhere near this load-carrying capacity, but I would have thought that this would fail the "obviousness" test as it's a scaling up issue. I suppose there might be the argument that the previous design was primarily for manouevering, not lift, but I still think there's an obviousness issu there.

Variable-weight neutral buoyancy doesn't necessarily need fuel.

The helium envelope(s) can contain smaller bags, filled with air - these can be inflated/deflated as required to vary buoyancy.

There must be some reason why they aren't using it in this design (possibly because inflating the air bags after load-drop takes too long?), but an airship certainly needn't lose helium to descend after losing weight.

Oh, the humanity!

Proceed to the trademark office and register "whirlyblimp" straight away. Do not pass go. Collect many hundreds of pounds.

I'm still not entirely clear on why blimpsters use Helium. It's outrageously expensive compared to Hydrogen. I thought by now everyone knew it was a combination of static electricity and the airship's doping compound that caused the Hindenburg fire.

Limited Military Use

Helium Venting

Gents/Ladies -

Yes you could suck helium from the lifting envelope and compress it in tanks, so keeping the valuable gas but doing away with its buoyancy. But high-pressure storage tanks are heavy, and ramming gas into them is a slow and power-hungry process. Compressors would be heavy too, as would the transmission to carry power from the ship's engines to them. Even if we were to build all this very heavy kit - much heavier than a few sets of rotors as in the JHL-40 - into an airship for this purpose, it would have to hover above the delivery point probably for hours, compressors at full bore, before the tension came off the sling lines and it could unhook without risk of losing gas. It would never be a proper flying crane.

Also - air ballonets inside blimp envelopes. Yes these do exist - you have to have them in a non-rigid ship, to keep the envelope fully inflated when you're below pressure height and the helium doesn't totally fill it. But you can't use them to meaningfully compress the helium - an envelope which could contain its contents at pressures usefully higher than ambient would be so heavy it couldn't fly. A flyable envelope would come apart - burst - if you tried to squash the helium down by squirting high-pressure air into the ballonets. Even if you made the whole envelope out of miracle supercloth or something, you'd still be lumbered with the slow, heavy compressors as in the storage-tank option.

The best practical option for a normal airship unloading is for it to take on water ballast via a pipe as stuff is disembarked. That's obviously fine at a mooring mast, and reasonably practical if hovering above the sea (though you need quite a muscular pump if hovering at all high up). It won't do at a construction site in Alaska or Siberia or the brazilian rainforest etc.

You could use nice cheap hydrogen - obviously they did in the Graf Zeppelin for ages without problems - and I'm aware of the Hindenburg theories. But the stuff leaks like the dickens, and it is quite dangerous. I don't think you could really sell that idea in the modern safety climate.

Hope that helps. As you can probably tell, I'm a bit of an airship geek.

Loads of opportunities

re: Helium Venting

@ Lewis Page - thanks for pointing that out - I never realised the ballonets (knew there must be a name for them apart from "big air bags"...) were related to the (non-)rigidity of the airship and just assumed they were entirely used for buoyancy control.

> Even if you made the whole envelope out of miracle supercloth or something

That reminds me, a few years back I wondered if a rigid airship containing *nothing* (no air, no helium, no hydrogen - just vacuum) would be feasible. I had it pointed out to me that no materials could withstand the pressures that would result. BUT if some sort of fabric could be made out of carbon nanotube fibres then that might work. Just extend the bracing struts inside to climb, and vice-versa. (a sort of concave-faced polyhedral inside-out blimp)

Another one for the "we'll build this when we discover an unobtanium mine" category I suppose...

Vacuum Ship

You're right, people have often pondered a vacuum ship, though it offers relatively little benefit. Helium (atomic weight 4, double molecule) and especially hydrogen (atomic weight 1, double molecule) are so much less dense than air (mostly nitrogen, atomic weight 14, double molecule - or even heavier oxygen) that you don't get a colossal boost in lift - roughly 7 or 40 per cent, compared to H or He. Plus you laugh at pressure height, of course. So it's useful, but not such as to justify the awful difficulties of making a huge, ultralightweight vacuum bottle or internally braced vac-sac. A convex rigid skin would seem likelier, though, as it would provide some bracing of itself. But consider what big pressure bottles look like with our materials tech: ships and submarines and space stations, much too heavy to float on their own buoyancy in 1-bar gas.

I think there was an Iain M Banks book where the airships were full of nanothin carbon vacuum spheres, super light but super empty. As in the book, though, by the time you can actually build a working vacuum airship you're probably so advanced that you would only do so for for a laugh. For everyday travel you'd just hop into your artificial-intelligence antigrav starship or whatever.

@lIsRT

"I wondered if a rigid airship containing *nothing* (no air, no helium, no hydrogen - just vacuum) would be feasible. I had it pointed out to me that no materials could withstand the pressures that would result. BUT if some sort of fabric could be made out of carbon nanotube fibres then that might work."

Materials do exist from which you can construct a vacuum chamber capable of withstanding the outside atmospheric pressure. But these are too heavy and metals tend to be required. Carbon fibres are useful in high tension applications, not in withstanding the high compression needed for a vacuum chamber. So the compressed air powered car being developed uses carbon fibre tanks, but with these the pressure to be withstood is inside the stretched tank, not outside the compressed tank. If you want your airship structure to be lightweight you have a better chance if internal and external pressures match or nearly match, hence the use of lighter than air gasses. The ideal shape for a vacuum chamber is a sphere, but as the size of the sphere increases the thickness needs to increase to reduce the risk of instability and inward collapse.

Compressors...

I hope we're not going to have another "decimation" moment..

But, the rotors would have to 'lift a load of forty tons' and hold it there whilst 'tis moved '200 miles' at airship speeds that'd be around 3 hours. You'll want a 4 hour endurance and ability to maintain lift with 3 engines for the safety margin. They suddenly sound significantly more substantial than a gas compressor and a couple of tanks.

I guess it depends how rapid a compressor you need and the actual fuel consumption of engines that produce 40+ tons of lift...

@andy gibson

Here's an obvious thought

Surprised that no one has mentioned it yet.

Since the problems occur mostly during dynamic loads (at the construction site),

why not tie the thing down to the ground near the construction site? With a few cables, the blimp could be supported by ground vehicles or tankers. These could also provide electrical power and/or gas for fuel and buoyancy.

How many tons?

I find the claims of the airship heavy lift brigade underwhelming. The typical payload of most heavy lifters, whether floating, rotary or fixed-wing, is about the same as one (1) ordinary road-going lorry. Even the Hindenburg and its kin only had about a 55-ton payload capacity, which must have really inconvenienced all those rich cruising types. "What do you mean, I can't take Frou Frou's kennel?"

JonB

Okay then. You want cross-connected rotors on the JHL (though you might not bother: the JHL-40 can simply drop its load if it has an engine failure and become an ordinary airship). Chinook rotors are cross connected, and two can lift about 25 tons of all-up Chinook. We need the equivalent of two Chinook rotor sets and transmissions - fifteen, eighteen tons of gear tops, probably less; an entire Chinook only weighs a bit over ten tons empty - to lift 40 tons and lots of extra fuel. Both the regular airship and the blimpcopter need engines and use fuel, but the blimpcopter as you rightly point out will use a lot more when it has an underslung load.

You would rather lift that 40 tons with helium, and then ram all the extra helium away into a pressure vessel when dropping loads. You'll need about 37,000 cubic metres of helium to lift 40 tons. Good pressure spheres can hold 300 bar, so you need about 150 cubic metres of high-pressure tanks to stuff the gas into at drop-off - an enormous, very strong metal ball as big as a house - not "a couple of tanks". Just the tankage alone will be hugely heavier than rotor sets, and we haven't even started on compressors and transmissions - ones able to squash down a cathedral-full of free gas to 300 bar in a matter of minutes. It isn't going to be a little diesel job, you know - I doubt that four jet engines would provide enough power to get it done inside a day either, not and provide hover thrust too. You'd probably need extra prime movers.

Seriously - it isn't going to work. All through the history of airships, people have struggled to control buoyancy without venting gas as load diminishes; even fuel burn over a long voyage is a serious problem. The Germans tried using special gaseous fuel that weighed the same as air - Blaugas - that worked pretty well. The Americans used condensers to reclaim water from the engine exhaust, and so replace missing fuel with water ballast - that's what those funny squares were on the sides of the Akron and Macon. Apparently it worked OK when running at speed, to provide air cooling for the condensers.

Nobody ever produced something that could cope with losing a big fraction of useful load fast without venting gas or taking on ballast. Nobody - nobody, not the Germans, not the Americans, not us - even tried storing meaningful amounts of lift gas aboard under pressure, because, as you see, it is totally impossible. Piasecki with his Heli-Stat and Boeing today had good reasons for using rotor lift for the droppable load - they are all professional engineers.

Helium venting - again

Big gas pocket filled with helium mounted on a frame with four lift/thrust units. The thing is neutrally buoyant so it floats and can be very efficient.

Folks are worried about the sudden increase in buoyancy when the load is dropped off. Why?

First of all the vertical thrust is the primary source of lift against the load. When the load is being 'dropped' the aircraft has to be descending. As it approaches the point at which the load on the lift cables is neutral, the power on the vertical thrusters is reduced to nil - remember helicopters can alter the angle of attack of the rotor blades allowing very, very quick adjustments to the amount of lift. So, where's the problem with sudden buoyancy? If the lift cables broke, then you'd pop up like a cork in a bath tub, but that is true of any heavy lift aircraft with vertical lift capability. As soon as the lift cable broke the avionics would back off the vertical thrust and the blimp would float free.

Which this reminds me of is the semi-submersible oil rigs used in deep water drilling, also the drilling/exploration ships. They use station keeping thrusters and/or tethers to maintain their position. But use standard buoyancy to stay afloat.

Regarding this aircraft, a couple of things come to mind. Looking at the design, there's a lot of empty space on top that could be used for solar panels. This would increase the efficiency further allowing the panels to supplement the thrusters and/or run the avionics. The thrusters themselves are show with exhausts. Perhaps a more effective set up would be to use electrical power, at least for the directional thrusters. A single highly efficient engine/generator could supply what is needed, supplemented by the solar when available. Last, there is no reason why supplemental lift cannot be provided by additional gas envelopes that are inflated with helium both to aid in stability and in the vertical lift when taking a load. The gas doesn't have to move instantly to be useful, as long as the lift/drop off operation doesn't need to be super express. Good grief the amount of solar power generated on the top of the craft should be equal to the task of moving some helium around.

Also, since the vertical lift rotors are not required for the aircraft to fly, the can be optimized purely for lift. I wonder whether the ducted fan engines crank out more 'lift' for the energy used than a freely rotating rotor?

IT

Start with facts. Look up Piasecki's patent Vectored Thrust Airship, p/n 4,591,112 issued 26 May 1986. It's definitely prior art, and according to patent law, reduced to practice. The patent's background information is well written, and as valid today as then. The claims are clear and cover every aspect required.

Since the patent office website doesn't list any patent applications or patents issued to Mr. Jess, I cannot determine what he's claiming as new and useful. His airship looks more like the ship in Piasecki's patent than Pi's prototype did.

Piasecki's prototype, built at minimum cost using a "war surplus" ZPG-2 airship envelope and most of four H-34 helicopters cobbled together on a lifting frame, was going to be used to determine how to manage extremely high air flows in close proximity to the envelope both in and out of ground effect.

It self-destructed during an early low-power turn-up. The project was subsequently abandoned.

Since I retired someone may have developed a procedure for doing a full-power turn-up on the ground. (This would eliminate the requirement for a test flight after every engine or gear-box change - a very desireable thing for helicopter operators.)

No-one has demonstrated the ability to do so when the air circulation is blocked on one side by what is supposed to be an impervious envelope.

If the JHL-40 starts out neutrally buoyant, with an underslung payload, after burning 2 to 4 tons of fuel per hour, it's going to have to do something interesting to get home after dropping off its' payload. It also appears that the system CG would shift, rising at least 50 feet - should be an interesting challenge.

Honestly...

...some of you academic-boffin-impractical-nerdy types have got your heads in the clouds most of the time, haven't you ?

There's an obvious solution to this "helium-venting" and "vacuum-spheres" and "negative-payload-stressing" etc.etc.

Carefully nail a tow-bar onto the back of this infernal homunculus, buy a trailer and dump your excess Helium in there ! And while you're at it, my old pick-up will carry double in my trailer what it carries in the back, so you could probably get 80 tons up there instead !

@JonB

Military aircraft can have a problem with centre-of-gravity changes when unloading large amounts of mass (either as bullets or bombs/missiles) - this is one reason for the amount of testing done before releasing an aircraft to full operational capacity (one of the reasons Eurofighter Typhoon has taken so long to become "fully" operational is because the original design allowed for the "loss" of mass due to missiles weighing a couple of hundreds of pounds - then someone "asked" them to add 500, 750 and 1000-lb bombs with added goodies like laser guidance kits etc and the designers wanted to make sure the aircraft could still fly after losing so much weight in one go).

The mass of gun ammunition, while significant enough to affect the amount of other "stuff" that can be carried overall, is not normally great enough that a few seconds firing will make that much of a difference to the overall mass of the aircraft. Recoil, on the other hand, can be an issue - especially for a helicopter if the gun is mounted low down and away from the centre of gravity; recoil will push the nose up and back. It will also cause the gun muzzle to wander slightly and mean that the bullets might not go exactly where you wanted...

The A10 has an additional problem - the recoil from the big gun is a significant proportion of the thrust it gets from the engines... so firing the cannon is like slamming on the brakes. Not a good thing when you are relying completely on forward movement to keep off the grass...

Some of you need to take a couple thermo classes...

Supposing you had 15,000HP to compress gas, you wouldn't be able to use it. Compression requires that heat be removed from the gas, and when you go to high pressures, that heat is far in excess of the potential energy that gets added to the gas. You'd have 15000HP in, a bit exiting the system as PE in the gas... and then you'd need radiators for at least 10000HP, which is somewhere around 75MW, if I'm not too tired to do math. I have no idea how much that kind of cooling equipment would weigh, but I'm reasonably sure that there's no way in hell it'd fly.

Plus do you have any idea how large a gearbox you'd need for that kind of power? Just the driveshaft for the compressor would be ridiculously large and heavy, even if you made it from the most modern high-modulus carbon fibers.

I assume that the lift rotors could provide downward thrust as well, to compensate for lost fuel weight, plus any CG change would happen while the ship is stationary. CG only comes into play in dynamic systems, so there should be ample time to adjust whatever needs adjusting.

And thanks Mr. Page for having a consistently realistic approach to physics and engineering. And for being hilarious.

Damn now it's 3 am and I'm thinking about power transmission shafts and compressors. I guess it's time for another round of odd dreams.

RE Read the story

It won't become suddenly boyaunt... the helium only suports the aircraft, not the load.... that whole nutrual boyancy thing.

Hence why it is a Airship COPTER.... the rotors are used for the extra lift to pickup and set down a load. A hybrid if you will. The idea being your not burning large ammounts of fuel to stay in the air when not carrying cargo, and so that your lift rotors are only used for lifting loads, thus giving you way more lift capacity then a normal heli.

Also as a side note have any of you ever used a crane? you don't just drop the load you set it down, give yourself slack on the line then undo the load. Ecencialy on this Blimb copter, you would set down the load (first by adjusting speed and pitch of rotars, or via the crane depending on the load) refind yor netrual boyancy (by turning off the lift rotors) slack the lines and then unhook and take off.

@ Gianni Straniero

Actually the cause of the Hindenburg burning at Lakehurst is still disputed, analysis of the fire does not support the dope theory as much as its proponents would like to admit.

Hydrogen IS too deadly to use; the Graf Zeppelin is pretty much the only airship to have ever had a long successful career whilst being lifted with hydrogen. If you want examples of other hydrogen-fed disasters, then choose from the British / American R38, the British super-ship the R101, the French record-breaking Dixmude or a terrible number of WW1 Zeppelins that burned in the air - all because of hydrogen and nothing to do with their doping.

Zeppelin themselves recognised the risk from hydrogen and designed the Hindenburg to be inflated with helium; however, the US refused to export the gas to Germany because of Nazi re-armament policies and the fear that it might be diverted into a military airship programme. So Hindenburg was inflated with hydrogen and made a successful first season of travel to the US. Over the winter when it was laid up, the ship's accommodation was expanded to make use of the extra lift provided by hydrogen. The airship never finished that season.

Skyhook

This must be the result of some particularly stubbon pedant falling for the 'go get a skyhook' joke and setting out to prove to the world that he *could* infact have got a skyhook if only it had been invented.